Inside this church it is possible to visit the Roman undergrounds by paying a tickets of 10€ per person. It is the best way to understand how was built Rome trough the centuries and how the ground level of the city raised of almost 15 meters (30 feet). You'll visit first a basilica of the 4th century AD and then 2 different Roman houses of the 1st and the 2nd century AD and a temple dedicated to the Persian god Mitra.